Are you one of those people who won't drink a Moscow Mule in anything other than a copper mug? Bad news...

...the Iowa Alcoholic Beverages Division is warning people against drinking the popular beverage out of those shiny mugs.

If a beverage has a pH level lower than 6, the copper can leak into the drink enough to make it poisonous. Moscow Mules fall below that.

If you DO love your MM in a copper mug, experts say to make sure that it has a stainless steel lining.